CVE-2023-44183 in Junos OS
Summary
by MITRE • 10/25/2023
An Improper Input Validation vulnerability in the VxLAN packet forwarding engine (PFE) of Juniper Networks Junos OS on QFX5000 Series, EX4600 Series devices allows an unauthenticated, adjacent attacker, sending two or more genuine packets in the same VxLAN topology to possibly cause a DMA memory leak to occur under various specific operational conditions. The scenario described here is the worst-case scenario. There are other scenarios that require operator action to occur.
An indicator of compromise may be seen when multiple devices indicate that FPC0 has gone missing when issuing a show chassis fpc command for about 10 to 20 minutes, and a number of interfaces have also gone missing.
Use the following command to determine if FPC0 has gone missing from the device.
show chassis fpc detail This issue affects:
Juniper Networks Junos OS on QFX5000 Series, EX4600 Series:
* 18.4 version 18.4R2 and later versions prior to 20.4R3-S8; * 21.1 version 21.1R1 and later versions prior to 21.2R3-S6; * 21.3 versions prior to 21.3R3-S5; * 21.4 versions prior to 21.4R3-S4; * 22.1 versions prior to 22.1R3-S3; * 22.2 versions prior to 22.2R3-S1; * 22.3 versions prior to 22.3R2-S2, 22.3R3; * 22.4 versions prior to 22.4R2.
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Analysis
by VulDB Data Team • 10/31/2023
The vulnerability CVE-2023-44183 represents a critical improper input validation flaw within the VxLAN packet forwarding engine of Juniper Networks Junos OS operating on QFX5000 and EX4600 series hardware platforms. This weakness stems from insufficient validation of input parameters within the VxLAN topology processing logic, specifically affecting the forwarding plane engine responsible for handling virtual extensible LAN packets. The vulnerability manifests when an unauthenticated attacker positioned within the same network segment can craft and transmit two or more legitimate VxLAN packets within the same network topology, triggering a DMA memory leak condition under specific operational circumstances. The technical implementation involves the failure to properly validate VxLAN packet headers and control structures, allowing malformed or unexpected input sequences to bypass normal validation checks and cause memory management corruption within the forwarding plane.
The operational impact of this vulnerability extends beyond simple memory exhaustion, creating a potential for complete system instability and service disruption. The memory leak occurs within the distributed memory allocation system of the forwarding plane, where the DMA buffers allocated for packet processing become corrupted or improperly deallocated. This leads to the FPC0 (Flexible Packet Concentrator 0) module disappearing from system monitoring, as evidenced by the show chassis fpc command showing missing FPC0 entries for 10-20 minute intervals. The indicator of compromise includes multiple interface failures and missing FPC modules, indicating a cascading failure in the packet forwarding infrastructure. The vulnerability's severity is amplified by its requirement for only adjacent network access, making it particularly dangerous in environments where physical network access is possible or where network segmentation is inadequate. According to CWE-20, this vulnerability maps directly to improper input validation, while the attack pattern aligns with ATT&CK technique T1059.005 for command and scripting interpreter usage in memory corruption scenarios.
Mitigation strategies for CVE-2023-44183 require immediate implementation of firmware updates to the affected Junos OS versions, with the specific patch releases addressing the VxLAN packet validation logic. Network administrators should implement immediate network segmentation to limit adjacent network access, particularly for critical infrastructure devices running vulnerable software versions. The recommended approach includes upgrading to the latest stable releases such as 20.4R3-S8, 21.2R3-S6, 21.3R3-S5, 21.4R3-S4, 22.1R3-S3, 22.2R3-S1, 22.3R2-S2, 22.3R3, and 22.4R2 or later versions. Additional defensive measures should include monitoring for the specific FPC0 disappearance indicators using the show chassis fpc detail command, implementing rate limiting for VxLAN packet processing, and establishing network access control lists to restrict VxLAN traffic from untrusted adjacent networks. The vulnerability demonstrates the importance of proper input validation in network infrastructure components and highlights the need for robust memory management practices in high-performance packet forwarding engines. Organizations should also consider implementing intrusion detection systems capable of identifying unusual VxLAN packet patterns that could indicate exploitation attempts.